ODBC Failure running a query until a linked table is opened

[Tideways]

Here's a strange scenario. We have an Oracle backend and its tables are linked to Access 2007 (accdb) with ODBC.


When a user runs a query that contains linked tables to the Oracle backend they receive an error "ODBC--connection to 'ebsstudents' failed".
I have found that if a user opens one of the linked tables first, when they subsequently run the query it works.
Although I'm delighted to have found a workaround, I'm more interested in working out what the problem is.
Any suggestions?

[orange]

Does an error number shows in the error message?

see http://support.microsoft.com/kb/325835

[Tideways]

Does an error number shows in the error message?

see http://support.microsoft.com/kb/325835

No, just the database name in the title of the message box and "ODBC--connection to 'ebsstudents' failed".
ebsstudents is the name of the dsn